[CF-metadata] Wrong definition for false-easting/false-northing?

From: Heiko Klein <Heiko.Klein>
Date: Mon, 09 Mar 2015 14:12:17 +0100

Hi,

the cf-convention in Table F.1 Grid Mapping Attributes explains
false-easting/northing as:

The value added to all abscissa values in the rectangular coordinates
for a map projection.



I think it must be 'The value subtracted from all abscissa values...':

    false_easting = 0 ... proj_x_axis_value(0) = -200000
is equivalent to
    false_easting = 200000 ... proj_x_axis value(0) = 0


or in proj.4-term (+x_0 = false_easting):
$ proj -I +proj=stere +R=6370000
-200000 -200000
1d47'57.196"W 1d47'54.005"S

heikok at pc4027:~$ proj -I +proj=stere +R=6370000 +x_0=200000 +y_0=200000
0 0
1d47'57.196"W 1d47'54.005"S



I tested it with the netcdf-java and other programs, too.
False_easting/northing values are subtracted from the x-Axis values.

Best regards,

Heiko

-- 
Dr. Heiko Klein                              Tel. + 47 22 96 32 58
Development Section / IT Department          Fax. + 47 22 69 63 55
Norwegian Meteorological Institute           http://www.met.no
P.O. Box 43 Blindern  0313 Oslo NORWAY

Received on Mon Mar 09 2015 - 07:12:17 GMT